Two pairs of crested ibises released into the wild last year on Sado Island in Niigata have been spotted guarding eggs, the Environment Ministry said Sunday.
The eggs could hatch in mid-April, which would result in the birth of the nation's first wild ibis chicks in 36 years, the ministry said.
The ministry believes a 3-year-old female released with a 3-year-old male last September nested on March 12, and the eggs were laid on Friday or Saturday.
It also said another pair — a 3-year-old male and a 2-year-old female that were freed last March — nested Friday and probably produced eggs as well.
"We're glad both pairs are now guarding eggs and hope that things will go well with the other ibises as well," said Kei Osada, the chief ranger in charge of wildlife protection on the island.
Another 12 pairs of ibises have been found together on Sado.
Japan's last wild indigenous crested ibis died in 2003. Japan has been trying to repopulate the species via artificial breeding techniques conducted with a pair of ibises presented as a gift from China in 1999.
Two pairs released through the government program laid eggs, in 2010 and 2011. But they failed to hatch because they were either thrown out of the nests or neglected by the birds.